There are many types of golf balls, such as solid golf balls (e.g. one-piece solid golf balls, two-piece solid golf balls, three-piece solid golf balls and the like) and thread-wound golf balls, and they are all supplied into the market in the form of a coated golf ball having a paint layer provided on the surface of the golf ball body. The paint layer is provided for the protection of the surface of the golf ball body or a marking provided thereon, for maintaining a white glossy appearance for a long period of time, or for improving abrasion resistance or scuff resistance against sand and the like during a bunker shot.
As a paint for golf balls, paint selected from the group consisting of urethane-based resin, polyester-based resin, epoxy-based resin, acrylic-based resin paint and the like have generally been used. The paint layer had excellent durability by coating the paint two or more times. In order to simplify the application process, it has been suggested to form the paint layer as only a single layer by using paint having excellent drying characteristics (Japanese Patent Kokai Publication Nos. 146930/1999, 51401/2000 and the like).
In Japanese Patent Kokai Publication No. 146930/1999, a golf ball paint comprising polyol containing urethane polyol as a main material and polyisocyanate as a curing agent is disclosed. In the golf ball paint, the equivalent ratio of isocyanate groups in the main material with respect to hydroxyl groups in the curing agent (NCO/OH) is within the range of 0.5 to 2.0, and the urethane polyol has a hydroxyl value of 55 to 130 mg KOH/g and weight-average molecular weight of not less than 4,000 to less than 10,000.
In Japanese Patent Kokai Publication No. 51401/2000, a golf ball comprising a polyurethane coating over the exterior surface is disclosed. The polyurethane coating includes a polyester polyol resin component and polyisocyanate component, and the polyester polyol resin component contains a neopentyl glycol resin.
However, golf balls for driving ranges are used such that they are repeatedly hit and washed. Therefore, it has been exactingly required for the paint of the golf balls to have excellent performance, such as impact resistance against repeated hitting, abrasion resistance after washing by brushing and stain resistance with respect to grass. Particularly, when the paint layer is formed into only a single layer, it is difficult to satisfy the entire performance requirements.